1. Field of the Invention
This invention relates to female sterilization methods and apparatus, and more particularly, to female sterilization methods and apparatus which operate by blocking the discharge of ova from the fallopian tubes into the uterine cavity.
2. Description of the Prior Art
A wide variety of techniques and apparatus have been developed in the past for either permanently or reversibly sterilizing the female reproductive organs. In U.S. Pat. No. Re. 29,345 (Erb) discloses a method and apparatus for ejecting a curable elastomeric composition through an aperture in a tip coupled to the end of an insertion device to form a plug within the fallopian tube. Although the tip adheres to the resulting elastomeric oviduct block, neither the tip nor the elastomeric material adheres to the tissue of the uterus or fallopian tube. The Erb plug injection system requires careful mixing and application of the elastomeric sealant and consumes a significant amount of time to accomplish the entire procedure, including the time during which the elastomeric material cures. Creation of the type of plug disclosed by Erb produces an elongated barrier which restricts and essentially eliminates the passage of both eggs and sperm through the fallopian tube. In a subsequent article entitled "Hysteroscope Oviductal Blocking With Formed-In-Place Silicone Rubber Plugs," Erb updates his prior fluoroscopic technique as disclosed in his patent by adopting a hysteroscopic procedure which permits optically monitored placement of the tip at the uterotubal junction area. At page 67, second column of this article, Erb confirms that his elastomeric plug does not adhere to the tissues of the female reproductive organs and may be withdrawn in one piece. In his last sentence at page 67 of his article, Erb indicates that his plugs are larger in diameter at both ends and narrower in the middle, a configuration important to retention of his oviduct blocking plugs.
In U.S. Pat. No. 4,135,495, Borgen discloses a method and apparatus for reversibly sterilizing the female reproductive organs. Borgen's invention involves abdominal surgery in which a cap is placed over and sutured to the fimbriated ends of the fallopian tubes. The caps prevent union of sperm and ova and prevent pregnancy. Subsequent abdominal surgery permits access to the caps which can be removed from the ends of the fallopian tubes without damage to the reproductive organs.
In U.S. Pat. No. 3,680,542, Cimber discloses an oviduct blocking device which is positioned during the course of abdominal surgery by inserting the device through the open end of the fallopian tube adjacent to the overy. Cimber's pointed guide member is removed through a surgical incision in the wall of the fallopian tube. If desired, subsequent abdominal surgery can be performed to remove the oviduct blocking plug to thereby reverse the sterilization procedure previously accomplished.
In an article entitled "Clinical Application of Hysteroscopic Sterilization Using Uterotubal Junction Blocking Devices," Hosseinian and Morales disclose the use of conical plastic plugs including bar-like retention devices as illustrated in FIG. 30-1 at page 235. In FIG. 30-2 at page 237, the authors disclose the proper method of inserting their plug into the uterotubal junction and retaining the plug in place by causing the plug-mounted barbs to penetrate into the tissue adjacent to the uterotubal junction. Hysteroscopic techniques were used to insert and remove the plug. At page 235, the device carrier is disclosed as being fabricated from stainless steel and including a tip with three grasping teeth, a shaft and a handle.
In an article entitled "Hysteroscopic Implantation of Uterotubal Junction Blocking Devices," Hosseinian, Lucero and Kim disclose uterotubal blocking plugs of a design substantially similar to that discussed in the article by Hosseinian described above. Further details of the device carrier are illustrated in FIGS. 3 and 4 at page 172.
In an article entitled "A Steerable Hysteroscope and Mechanical Tubal Occlusive Devices," Brueschke, Zaneveld, Wilbanks, Archie and Uretz disclose uterotubal plugging devices of the type illustrated in FIG. 6 at page 189. The disclosed conical plugs include metallic retention anchors or barbs "A" with a medical grade silicone rubber body "B" having a threaded retention member for securing the plug to a delivery wire.
In an article entitled "Anatomic and Physiological Factors Affecting the Development of Transcervical Sterilization Techniques," Eddy and Pauerstein in FIG. 2-8 at page 18 disclose the use of a Silastic sphere lodged in the lumin to occlude the lumin and prevent pregnancy.
In an article entitled "Hydrogel Tubal Blocking Device: P-Block," Burndin discloses an oviductal blocking device having a hydrogel body and two millimeter wide nylon wings which prevent expulsion from the fallopian tube before hydratization of the blocking device and subsequent water retention induced swelling. FIG. 31-1 at page 241 depicts the hydrogelic tubal blocking devices disclosed in the article.
In U.S. Pat. No. 3,909,852, Homsy discloses an implantable substitute structure for the middle ear bony chain. A rigid strut 12 maintains a fixed spacing between ends 14 and 16 which are fabricated from growth promoting porous material such as carbon bonded by PTFE plastic. The interior surfaces of pads 14 and 16 are covered with pore closing means for the express purpose of preventing tissue growth in this area which might adversely effect the sound transmitting qualities of the device. Such pore closing means is discussed in detail at column 2, lines 33-46 of the Homsy patent.